fix: move from devenv to nix flake

documentation/manual/de/book/tomorrow-night.css

documentation/manual/de/mdbook-admonish.css

documentation/manual/de/mermaid-init.js

documentation/manual/de/mermaid.min.js

documentation/manual/de/source/01-Einleitung.md

documentation/manual/de/source/02-Erste-Schritte.md

documentation/manual/de/source/404.md

documentation/manual/de/source/SUMMARY.md

documentation/manual/de/source/imprint.md

documentation/manual/de/theme/book.js

flake.lock

flake.nix

go.mod

makefiles/changelog.mk

makefiles/color.mk

makefiles/conan.mk

makefiles/directories-go-lib.mk

makefiles/directories-go-utilities.mk

makefiles/directories-platform-part.mk

makefiles/directories-standard.mk